Steam-control device



Aug. 20, 1929. G N 1,725,011

STEAM CONTROL DEVICE Filed Jan. 26, 1928 Patented Aug. 211, UNITED STATES 1,725,011 PATENT OFFICE.

GUSTAV MENZ, OF WILHELMSHAVEN, GERMANY, ASSIGNOR TO SIEMENS-SCHUCKERT- WEBKE .AKTIENGESELLSGHAIT, OF BERLIN-SIEMENSSTADT, GERMANY, A COB1'O BATION OF GER-MARY.

Application filed January 26, 1928, Serial 1T0.

My invention relates to a steam control device, and more specifically to a valve control gear which is particularly suitable for high-pressure .steam turbines.

Control valves for high-pressure steam turbines may be of the single-seat or the double-seat type. Double seat valves have disadvantages in so far as it is almost 1mposssible to keep them absolutely tight, while single seat valves require very strong servo-motors, since the pressure upon the valves is very considerable. This results in very large stem diameters, which in turn cause considerable leakage losses.

The object of my invention is to provide a controlgear or regulating device for highpressure steam tur ines, which permits of the use of single seat valves and small servomotors.

I attain this result by providing a balancing device by means of which the chamber or space above the valve in which prevails a higher pressure may be put in communication with the chamber or space below the valve in which prevails a lower pressure, whereby the valve is balanced.

An embodiment of my invention is illustrated by way of example in the drawings aflixed hereto and forming part of my specification.

In Fig. 1 of this drawingmy improved conitrol gear is shown in vertical section, an

Fig. 2 represents a slight modification of the valve casin Referring to i 1, 2 is the cone or plug of the control va ve disposed in casing 1 with slight clearance 6 between the enlarged guilclling portion of the value and. the caslng wa The steam to be controlled enters the valve casing through the branch 3 and escapes from it towards the turbine through the branch 4. The steam pressure p in the branch 4 is lower than the pressure p, in the branch 3. In the chamber 5 above the valve cone 2 there prevails at first the pressure p -This chamber 5 may also be placed in direct communication with the branch 1;, by a throttling pipe 30, controlled by a valve 31, as indicated in Fig. 2. From the chamber 5 a pipe 21 leads to the balancing device22 and from this device a pipe 23 leads to steam outlet 4 of the valve casing. The suri faces f f f, are so proportioned that the instance, be designed as STEAM-CONTROL DEVICE.

249,705, and in Germany September 11, 1926.

pressure in the chamber 5 closes the valve when the balancing device is rendered inoperative. The balancing device 22 may at first be used as device for opening the main valve. Under these conditions the device itself is closed before starting the turbine. The chamber 5 is in communication with the branch 3 and the main valve is closed. If now the balancing device 22 which may, for and operated valve) is. opened, steam from the branch 3 will flow through chamber 5 and the balancing device 22 by way of its valve 7 into the branch 4. Since the clearance between the guide portion of the valve 2 and the valve casing 1 as well as the balancing device 22 act as throttling members a pressure will exist in the chamber 5 whichv depends upon the size of the cross-sections of the two throttling areas. The size of the first crosssectional area (clearance 6 between the guide portion of thevalve 2 and the valve casing) located between the branch 3 and the chamber 5 is definitely fixed by the construction of the valve. The size of the second cross-sectional area may be adjusted by opening or closing the valve 7 of device 22. The main valve is opened by admitting oil underneath the piston 12 of the servo-motor 8 and then slowly opening the valve 7 of device 22 by any suitable means until the valve 2 rises and takes up the desired position.

The mechanism is well adapted for automatic operation, .as the drawing shows. The valve 2 is operated by an oil control piston 12 reciprocating in a cylinder 8 as,prev1ously mentioned. The adjustment of the piston 12 is initiated by a centrifugal governor 10 actuating the control slide piston or pilot valve 9 by means of which oil under pressure is admitted above or below the piston 12, tending to raise or lower valve 2. Assuming that the main valve 2 is to be opened and the pilot valve 9 is in its central position. So long as the valve 7 of the device 22 rests on its seat, the main valve 2 is not balanced and cannotbe opened by the servo-motor piston 12. During the regulating motion tendency to initiate the opening the pilot valve 9 moves downward and admits oil under pressure underneath the piston 12 so that a force tending to open the valve 2 is developed. At the same time oil under pressure is forced through the pipe 20 above a second forces oil through the ipe 19 and underservo-motor piston 14sliding in a-cylinder 13 the iston rod 15 of which is moved downward t ereby. This piston rod 15 carries at its lower portion the pilot valves 32 and 33 of a third servo-motor 17, the piston 18'of which operates the valve cone 7 of the balancing device 22. Through these pilot valves 32 and 33 at this particular time pressure oil is admitted through the pipe under the servo-motor piston 18 so that valve 7 is slightly lifted off its seat. The pressure difference between the top and bottom of main valve 2 is thus balanced, and the piston 12 can 'now raise valve 2 until the follow-up sleeve 11 actuated by piston 12 exerts its control efiect upon the oil supply in Well known'manner and stops the piston movement, until the pilot valve 9 is further raised by the governor or other control means.

The system shown in the drawing functions automatically to maintain the valve 2 in position, when once adjusted, for the following reasons: Assuming the pressure p, rises. The valve 2 will then have the tendency to ascend. The piston 12 in that case neath the piston 1 .1 and t us pushes that piston-upwards. When the piston 14 performs a short upward motion oil under pressure is forcedthrough the pipe 24 above the piston 18iand .the valve 7 is thus closed. This causes the pressure in the chamber 5- to rise wherebythe valve 2 is forced back again to its previously set position. The system thus 'has the tendency to return automatically to its position of e uilibrium.

Various modi cations and changes may be made without departing from the spirit and the scope of the invention, and I desire, therefore, that only such limitation shall be art.

I claim as my invention: p 1. In a valve gear for steam turbines, of

I the class specified, a balancing device by the balancing device is closed the valve isclosed by a loadin pressure itin the closing irection.

2. In a valve gear for steam turbines, of the class specified, a balancing device by (p acting upon means of which the steam chambers above and below the valve are adapted to be placed in communication in'such a manner that the placed thereon as are imposed by the prior action of the steam pressure opposing the regulating motion is balanced, and means for automatically regulating said balancing de-. vice in dependence upon the valve motion in such a manner that when said valve tends to 7 open the loading pressure is reduced, and when the device is closed it is increased.

3. In a valve gear for steam turbines, of the class specified, a balancing device bymeans of which the steam chambers above and below the valve are adapted to be placed in communication in such a manner that the action-of the steam pressure opposing the regulating motion is balanced, the

areas loaded by the pressure of the inconi- 8'0 ing fluid acting in the opening direction of the valve, and the pressure ,of the outgoing fluid acting in the same direction, and the pressure acting upon the valve in the closing direction being so proportioned, that when the balancing device is closed the .valve is closed by a loading pressure acting upon it in the closing direction, and means for automatlcally regulatingsaid balancing device in dependence upon the valve motion in such a manner that when said balancing device is opened, the loading pressure is reduced and when the device is closed it is increased.

4:. In av'alve gear for steam turbines, of

the class specified, a balancing device by means of which the steam chambers above and below the. valve are adapted to be placed in communication, a regulating valve and a control piston for operating it, an auxiliar oil control gear adapted to be operated by I I 5. In a valve gear'for controlling the admission of pressure fluid, a main valve chamber and a. main valve contained therein, a balancing device forcontrollin pressure difference between the two sidesofr the valve chamber, above and below the valve by which difference said valve tends to close, said balancing device comprising a 115 by-pass connecting the two chamber si and a balancing valve in said bypass, operating means for setting said main valve into the desired position, and means actuated by the motion of the main .valve for operating said pressure said balancing valveqto reduce diflerence when the main valve tends to close, and to increase said difference when the main .valvetends to open beyond the position for which it was set. i

- 6.-In a valve gear for controlling the ad- 125 mission of pressure fluid, a. main valve chamber and an unbalanced main valve disposed thereln, a mam servo-motor for operating said main valve, a pilot device actua" the loading pressure is the ated by outside means for controlling the action of said main servo-motor, an equalizing connection between the two sides of the main valve for balancing said valve, a

' control valve in said connection for controlling the balancing effect, a second servomotor for operating said controlling valve, and a second pilot device for controlling said second servo-motor, an auxiliary servomotor for actuating said second pilot device, said auxiliary motor being piloted by said main servo-motor and its pertaining pilot device.

7. In a valve gear for controlling the admission of pressure fluid,- a main valve chamber and an unbalanced main valve disposed therein and having a fluid leakage t e path from the fluid supply portion of chamber towards the side of the valve opposite to its fluid discharge side, to produce a desired seating pressure upon the valve, a main servo-motor for operating said main valve, a pilot device actuated by outside means for controlling the action of said servo-motor, an equalizing connection be tween the two sides of the main valve for balancing said valve, a control valve in said connection for controlling the balancing effect, a second servo-motor for operating said controlling valve, and a second pilot device for controlling said second servo-motor, an auxiliary servo-motor for actuating said second pilot device, said auxiliary motor being piloted by said main servo-motor and its pilot device.

In testimony whereof I affix my signature.

GUSTAV MENZ. 

